From the late sixteenth century, foreign engineers promoted new hydraulic technologies in England. Yet, their techniques were not alone sufficient to implement wetland improvement at a grand scale. Drainage projects generated local controversy almost everywhere they were proposed. Disputes pivoted on thorny questions about who was empowered make decisions about the management of water and land, and by what means. Under the early Stuarts, the crown and its ministers began to act as instigators and facilitators driving forward fen projects. The use of increasingly coercive methods to suppress and circumvent local opposition became entangled in wider constitutional controversies about the limits of royal authority and definitions of the public good. Wetland communities were active participants in debates about the economy and morality, environments and justice, consent and legitimate authority. Customary politics proved a powerful force, unravelling a litany of proposed projects in the early seventeenth century. This impasse was broken when Charles I launched the first state-led drainage project in Hatfield Level in 1626, yoking coercive authority to transnational expertise.